board/visionfive2: add spi-nor image

Builds the spi-nor.img together with the sdcard.img.
Readme is extended with SPI NOR flash writing instructions
and recovery.

The spi-nor.img layout is based on the following document:

https://doc-en.rvspace.org/VisionFive2/Boot_UG/JH7110_SDK/boot_address_allocation.html

Signed-off-by: Lukasz Tekieli <tekieli.lukasz@gmail.com>
[Arnout: extend readme.txt with paragraph that either boot mode works.]
Signed-off-by: Arnout Vandecappelle <arnout@mind.be>

board/visionfive2/genimage_spi-nor.cfg

@@ -0,0 +1,36 @@
+flash nor-16M-256 {
+	pebsize = 4K
+	minimum-io-unit-size = 256
+	numpebs = 4096
+}
+
+image spi-nor.img {
+	size = 16M
+
+	flash {
+	}
+
+	flashtype = "nor-16M-256"
+
+	partition spl {
+		image = "u-boot-spl.bin.normal.out"
+		offset = 0K
+		size = 512K
+	}
+
+	partition uboot-env {
+		offset = 960K
+		size = 64K
+	}
+
+	partition uboot {
+		image = "u-boot.itb"
+		offset = 1M
+		size = 4M
+	}
+
+	partition reserved-data {
+		offset = 6M
+		size = 10M
+	}
+}

board/visionfive2/post-image.sh

@@ -0,0 +1,4 @@
+#!/bin/bash
+
+support/scripts/genimage.sh -c board/visionfive2/genimage.cfg
+support/scripts/genimage.sh -c board/visionfive2/genimage_spi-nor.cfg

board/visionfive2/readme.txt

@@ -12,12 +12,27 @@ How to build
 $ make visionfive2_defconfig
 $ make
 
+Once the build process is finished you will have two images
+in the output/images/ directory:
+- sdcard.img
+- spi-nor.img
+
+How to write the SPI NOR flash
+=============================
+
+If you have a booting device use u-boot and tftp:
+
+  # tftpboot 0x82000000 spi-nor.img
+  # sf probe
+  # sf update 0x82000000 0x0 {filesize}
+
+Otherwise, follow the recovery instruction:
+
+https://doc-en.rvspace.org/VisionFive2/Quick_Start_Guide/VisionFive2_SDK_QSG/recovering_bootloader%20-%20vf2.html
+
 How to write the SD card
 ========================
 
-Once the build process is finished you will have an image called "sdcard.img"
-in the output/images/ directory.
-
 Copy the bootable "sdcard.img" onto an SD card with "dd":
 
   $ sudo dd if=output/images/sdcard.img of=/dev/sdX
@@ -27,7 +42,12 @@ Preparing the board
 
 Connect a TTL UART cable to pin 6 (GND), 8 (TX) and 10 (RX).
 
-Change the boot mode pins to SD card booting (RGPIO_0=1, GRPIO_1=0):
+Use the correct mode for booting:
+- SD card RGPIO_0=1, GRPIO_1=0
+- SPI NOR flash RGPIO_0=1, GRPIO_1=1
+
+Note that Buildroot puts the bootloader both in SPI NOR and on the SD card,
+so after flashing as instructed above, either boot mode should work.
 
 https://doc-en.rvspace.org/VisionFive2/Quick_Start_Guide/VisionFive2_SDK_QSG/boot_mode_settings.html
 

configs/visionfive2_defconfig

@@ -1,8 +1,7 @@
 BR2_riscv=y
 BR2_SYSTEM_DHCP="eth0"
 BR2_ROOTFS_OVERLAY="board/visionfive2/overlay"
-BR2_ROOTFS_POST_IMAGE_SCRIPT="support/scripts/genimage.sh"
-BR2_ROOTFS_POST_SCRIPT_ARGS="-c board/visionfive2/genimage.cfg"
+BR2_ROOTFS_POST_IMAGE_SCRIPT="board/visionfive2/post-image.sh"
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="6.8.2"